1. Field
Power driven dental scalers are well known. Of particular interest herein is a dental scaler having a scaling tip with an improved work surface configuration.
2. State of the Art
Of the power driven dental scalers currently available, most common are scalers utilizing compressed air or an electrical ultrasonic transducer to cause the scraping type work tool to vibrate.
Typical of the earlier air-driven dental scalers are those of U.S. Pat. No. 3,820,529 and U.S. Pat. No. 3,444,622 to Mills et al, which scalers utilize an air-driven ball contained in a chamber. Movement of the ball against the walls of the chamber imparts vibration to the chamber which vibrations are then transmitted to the scraping tool. A more recent type of air-driven scaler, described in U.S. Pat. No. 3,526,962 to Fuerst, utilizes a rotatable mandrel which has an irregularly-shaped tip engaged with a reciprocable block in which the mandrel tip is received.
It is characteristically a problem of these air driven scalers that much of the vibrational energy generated by the vibrator motor is transferred to the handle portion of the dental scaler rather than to the scraper work tool. Moreover, the modes of vibration of these scalers may change as moving parts of the vibration generating mechanism wear with time.
In U.S. Pat. No. 3,703,037 to Robinson, there is described a dental scaler which utilizes an electrical ultrasonic transducer to provide constant modes of vibration for coupling with particular types of work tools. One disadvantage of the ultrasonic scaler, however, is the cost of the transducer and its associated ultrasonic generator.
A recent improvement in air-driven dental scalers is disclosed in U.S. Pat. No. Re. 29,687 to Sertich. This dental scaler has very few moving parts as compared to the aforementioned mechanically complicated air-driven scalers and provides efficient transfer of vibrational energy to a scraping-type work tool with relatively little vibration being transferred to the handle portion of the instrument. Moreover, the Sertich-type scaler provides uniform modes of constant vibration which may be matched with the vibratory modes of various types of work tools without the need for any complicated electronic components.
The Sertich-type dental scaler achieves these advantages in part by including a single, rigid vibratable tube mounted on resilient support washers disposed at or near the theoretical vibratory nodes characteristic of the natural vibrational mode of the tube. A work tool, such as a scraper or a pick, is typically secured to the working end of the vibratable tube by a connection between an externally-threaded work tool shank and an internally threaded portion of the tube.
The mode or pattern of vibration of the vibratable tube of the Sertich-type scaler is characteristically one which during one oscillation or cycle of vibration traces a path that may vary from circular to oval or ellipsoidal in shape. It has been found that this particular vibratory orbit provides maximum efficiency of energy transfer from the tube vibrating mechanism to the working tip.
There has been some attention given to the matching of vibratory mode to a particular scaler tip configuration. For example, in U.S. Pat. No. 2,990,616 to Balamuth et al there is described a preferred mode of vibration which is elliptical in configuration. The described elliptical motions of a tapered vibrating tip provide efficient cutting action for forming a hollowed out portion in a hard, dense material such as tooth dentin. The Balamuth patent discloses one tip configuration for use by a dentist in boxing, that is, in preparing cavities of rectangular cross-section. The tip has an arcuate, somewhat tapered shank and is square in cross-section near the working end of the tip. One problem with the Balamuth tip, however, is that the sharp longitudinal edges of the scaling tip may severely damage teeth by chipping or cutting too far into tooth dentin.
There is, therefore, need for a novel scaler tip for use with a dental scaler having a vibratory mode so as to provide efficient scaling without the hazards of damage to teeth or gums.